Notes on the Influence of Drought on the Bush Remnants of the Manawatu Lowlands

SUMMAR Y: The data of Atkinson and Greenwood (1972) on drought damage to trees in 1969.70 in two bush patches in the Manawatu district are reassessed, and an index of drought susceptibility based on their data used to classify species into three categories of susceptibility. The results of this categorisation are compared with independent data on the effects of the 1972-73 drought on the nearby bush remnant at Ashhurst Domain. The behaviour of species in all three bush patches is shown to be similar, Comparison is also made with scanty data from other bush remnants, and with the upper altitudinal limits of the species in each category. The results suggest that the different tree species involved have intrinsically different susceptibilities to water stress, which partially explains why in nature they are sorted into hydrologically different situations. The potential application of knowledge on the drought susceptibility of species to reserve management on the one hand, and to past climatic reconstruction using dendrochronology and population structure on the other, is pointed out.